Mortise locks and latches have been implemented for over a century. Generally, mortise locks and latches require a rectangular hole in the door edge for installation, and for all intensive purposes are identical, the only difference is that a mortise lock actually locks whereas a mortise latch only latches. The present invention is compatible with either type of mortise door system. For the purposes of brevity a mortise latch will be described only, keeping in mind that the present invention may be used with a mortise lock just as easy.
A mortise latch (mortice lock in British English) is one that requires a pocket—the mortise—to be cut into the door or piece of furniture into which the lock is to be fitted. In most parts of the world, mortise latches are generally found on older buildings constructed before the advent of bored cylindrical locks, but they have recently become more common in commercial and up market residential construction in the United States. The parts included in the typical mortise lock installation are the lock body (the part installed inside the mortise cut-out in the door); the lock trim (which may be selected from any number of designs of doorknobs, levers, handle sets and pulls); a strike plate, or a box keep, which lines the hole in the frame into which the bolt fits; and the keyed mortise cylinder which operates the locking/unlocking function of the lock body. However, in the United Kingdom, and certain other countries, most mortise locks on dwellings do not use cylinders, but have lever tumbler mechanisms. The installation of a mortise latch cannot generally be undertaken by the average homeowner since it is labor intensive and requires a working knowledge of basic woodworking tools and methods. Many installation specialists use a mortising jig which makes precise cutting of the pocket a simple operation, but the subsequent installation of the external trim can still prove problematic if the installer is inexperienced. Although the installation of a mortise latch actually weakens the structure of the typical timber door, a mortise latch does offer more versatility than a bored cylindrical latch, both in external trim, and functionality. Whereas the latter mechanism lacks the architecture required for ornate and solid-cast knobs and levers, the mortise latch can accommodate a heavier return spring and a more solid internal mechanism, making their use possible. Furthermore, a mortise lock will typically accept a wide range of other manufacturers' cylinders and accessories, allowing architectural conformity with lock hardware already on site. Some of the most common manufacturers of mortise locks in the United States are Baldwin, Emtek, Falcon, Schlage, and Sargent. Also, many European manufacturers whose products had been restricted to “designer” installations have recently gained wider acceptance and use.
Typical mortise latches or locks are offered in a complete range of functions designed for commercial and institutional applications. They are engineered for strength and performance, and precisely manufactured to exacting standards. Components are interchangeable for functionality and versatility. Some mortise locks are designed with high quality components to provide high security, performance and durability. They are well suited for commercial facilities with exposed perimeter doors, such as warehouses, factories and malls. Other facilities that may implement mortise door locks are hospitals, schools, universities, factories, and office buildings. Still other mortise door locks are designed for use on those openings that are subjected to expected extreme abuse, vandalism, and malicious impact, such as in asylums, detention centers, commercial facilities with exposed perimeter doors as in warehouses and malls.